ACE701C

High Efficiency Low Noise PFM Boost DC/DC Converter

VER 1.3

6

Capacitor Selection

Ignore ESR of capacitor，the ripple of output voltage is:

So large value capacitor is needed to reduce ripple. But too large capacitor value will slow down system

reaction and cost will improve. So 100uF capacitor is recommended. Larger capacitor value will be used

in large output current system. If output current is small (<10mA), small value is needed.

Consider ESR of capacitor，ripple will increase：

When current is large, ripple caused by ESR will be main factor. It may be greater than 100mV。The ESR

will affects efficiency and increase energy loss. So low-ESR capacitor (for example: tantalum capacitor) is

recommend or connect two or more filter capacitors in parallel.

Diode Selection

Rectifier diode will affects efficiency greatly，Though a common diode (such as 1N4148) will work well for

light load，it will reduce about 5%~10% efficiency for heavy load，For optimum performance, a Schottky

diode (such as 1N5817、1N5819、1N5822) is recommended.

Input Capacitor

If supply voltage is stable, the DC-DC circuit can output low ripple, low noise and stable voltage without

input capacitor. If voltage source is far away from DC-DC circuit, input capacitor value greater than 10uF

is recommended.

Test Circuits

ACE701C